When designing a knitted article, a technique has been conventionally used in which an image of a stitch loop constituting a knitted fabric is simulated and created using data for knitting a knitted fabric, and then the simulation image of the knitted product is displayed (see Japanese Unexamined Patent Publication JP-A 7-70890 (1995)), for example). In this technique, image processing is performed in which image data of a knitting yarn is pre-stored as a yarn sample, the shape, the position, and the contrast in each portion of each stitch loop are determined based on the data for knitting a knitted fabric, and after dividing into a plurality of segments, the image data of the yarn sample is associated with the divided segments to be synthesized as a loop. For the image data that has been divided into segments, the shape of each loop and the overlap with the underlying loop are determined based on the data for knitting a knitted fabric. A spline approximation is performed on the image data of the knitting yarn that has been segmented in accordance with the shape of the loop, a mask is created for the overlap with the underlying loop to keep the exposed portion of the underlying loop, and the image of the knitted fabric is thus simulated. It is possible to express fuzz by making the periphery of the yarn sample rough, and it is also possible to express twine of yarns by adding oblique lines on the yarn sample.
When simulating a knitted fabric using a fuzzy knitting yarn in conventional knit design methods, it is impossible to reflect fuzz sufficiently in a method without consideration to fuzz, and fuzz is emphasized so significantly that the fabric often looks unnatural in a method with consideration to fuzz. This is because even with consideration to fuzz as image data, it is impossible to express an aspect in which the fuzz is flattened by an adjacent knitting yarn during knitting.
In a simulation of a stitch loop as in JP-A 7-70890, fuzz around a knitting yarn or twine of knitting yarns is expressed artificially and is difficult to bring close to the feeling of a knitted fabric knitted with actual knitting yarns. In particular, in the spline approximation on the segments, when the segments are simply connected to each other in a curved section, an edge appears in a section connecting between a segment and a segment, and thus a smooth connection is realized when both ends of the segments are made soft and then overlapped each other. However, in such a connection, it is impossible to assure that fuzz crossing between the divided segments is expressed continuously as the original, and it is difficult to express a natural feeling of a knitted fabric in a simulation image even when image data of a fuzzy knitting yarn is actually used as a color sample.